The leading student insurer is warning freshers going to university or college this autumn that they may be targeted by organised gangs of thieves. Endsleigh Insurance, which is part-owned by the National Union of Students, also fears that up to thousands of cash-strapped students could be driving uninsured - which as well as being illegal leaves open the possibility of a crippling long-term financial burden should they have an accident.

Nearly half of all thefts from students take place in the first eight weeks of the autumn start to the year. The NUS, which is about to launch an awareness campaign aimed at reducing crime against students, says this bunching of thefts underlines the need for those wanting insurance to sort it out as early as possible, even before actually going to university.

Cheltenham-based Endsleigh, which claims to be behind 75 per cent of all the insurance students take out, expects to pay out on up to thousands of claims totalling millions of pounds for thefts in the first few weeks of this academic year. The company already has claims in for the year just starting, and warns that new students - freshers - are particularly at risk. They often have new hi-fis, personal computers and better clothes, and in the excitement of their first few weeks away from home, security is often the last thing on their minds.

Endsleigh has known examples where gangs of thieves have swept through halls of residences, clearing out the rooms of 20 new students. "There is a huge amount of organised crime," says Stuart Wartalski, marketing operations manager at Endsleigh. "It's not just hi-fis and computers; it's designer trainers and a pair of good quality jeans."

Students should also beware of thieves among their own number.

Some colleges have block insurance policies for students in halls of residence, with the cost of premiums built into rent.

Endsleigh offers contents insurance starting at pounds 26 for someone living in a hall of residence wanting pounds 2,000 of possessions insured. That may sound high but Endsleigh says its experience is that the replacement cost of most students' possessions is pounds 2,000 or more. For students living out of hall - often in what are high-risk properties - premiums start at pounds 36.

The policy covers up to pounds 300 of computer equipment but not bicycles - Endsleigh has separate policies for bikes (from pounds 36 for a bike worth pounds 200) and more valuable computers. It also gives cover of up to pounds 50,000 against personal injury from mugging or assault. Endsleigh notes the recent conviction of a gang of muggers in Cambridge that had carried out more than 100 violent attacks and robberies against students in a year.

Bikes are an area to look out for with any insurance policy. Under a standard contents policy they will only be covered if they are stolen from your room or flat. To be covered when you lock them outside the union building, for example, you will need to be covered for "all-risks", which normally means getting an extension to an existing policy or special insurance - both of which will cost.

Another alternative to students taking out their own contents insurance is to get an extension on their parents' policy. Sun Alliance is unusual in that it makes no extra cost for this extension on its Connections contents policies.

If a bike is already covered "all-risks" under a policy taken out for the parental home, there may seem no need for additional insurance if the bike is taken to university. But Endsleigh's Mr Wartalski warns that it is important to check the small print to ensure the cover is still intact for students living away from home. There can be restrictions to "all-risks" extensions. If the policy is not clear, ask the insurer.

Another problem of using parents' insurance is that they risk losing any no-claims bonus if the student claims.

Separately, the NUS - concerned that student drivers get a rough deal from insurers, so that some are put off altogether and drive uninsured - has negotiated a special motor insurance deal from Endsleigh which claims to offer savings of up to 30 per cent. With even third-party insurance costing as much as the value of many students' cars, the fear is that as many as thousands may be driving without insurance.

Douglas Trainer, NUS president, says: "We became concerned that insurance companies' offers were far too high for students on the breadline and many refused to even quote for under-21s."

Endsleigh says its claims experience tells it that there are uninsured students, despite the fact that it is a criminal offence and leaves them unprotected against personal injury claims should they get into an accident.

On quotes, Endsleigh gives the example of a 20-year-old woman studying fine arts in Cheltenham who has a 1989 Vauxhall Nova 1300L. Four companies approached - Frizzell, Guardian, GA Direct and Norwich Union - would not quote at all because of the student's age, it says. Endsleigh quoted pounds 243 for third-party cover, compared with more than pounds 300 from four other companies that would quote. Direct Line's quote - through its Privilege subsidiary - was pounds 392, according to Endsleigh.

Tourists are limp, leaderless and distinctly UnAustralian

Andrew Grice: Inside Westminster

Blairites be warned, this could be the moment Labour turns into Syriza

The mystery of Britain's worst naval disaster is finally solved - 271 years later

Exclusive: David Keys reveals the research that finally explains why HMS Victory went down with the loss of 1,100 lives

'I saw people so injured you couldn't tell if they were dead or alive'

Nagasaki survivors on why Japan must not abandon its post-war pacifism

The voter Obama tried hardest to keep onside

Outgoing The Daily Show host, Jon Stewart, became the voice of Democrats who felt the President had failed to deliver on his ‘Yes We Can’ slogan. Tim Walker charts the ups and downs of their 10-year relationship on screen